1,25‐Dihydroxyvitamin D₃ enhances NK susceptibility of human melanoma cells via Hsp60‐mediated FAS expression

Abstract

The active metabolite of vitamin D 3 , 1a,25(OH) 2 D 3 , displays anticancer effects by regulating cell cycle and apoptosis in many cancer cells. However, it has not been determined whether 1a,25(OH) 2 D 3 increases the susceptibility of cancer cells to NK cells. Here, we investigated the anticancer effect of 1a,25(OH) 2 D 3 in human melanoma cell lines by investigating enhancement of NK susceptibility and elucidating the mediator of NK cytotoxicity. 1a,25(OH) 2 D 3 -resistant melanoma cells (G-361 and SK-MEL-5) treated with 1a,25(OH) 2 D 3 showed higher susceptibility to NK cells with up-regulation of Fas expression. Furthermore, G-361 cells treated with 1a,25(OH) 2 D 3 showed significantly increased caspase activity. In addition to Fas up-regulation, expression of heat shock protein 60 (Hsp60) was elevated by 1a,25(OH) 2 D 3 . Increased expression of Hsp60 by 1a,25(OH) 2 D 3 was related to not only up-regulation of Fas expression but also to NK susceptibility of G-361 cells. Taken together, our data suggest that 1a,25(OH) 2 D 3 acts as an anticancer agent by increasing expression of Fas on the surface of melanoma cells through Hsp60 induction and strengthens caspase sensitivity to Fas-mediated apoptotic pathway by NK cells. 1a,25(OH) 2 D 3 treatment may therefore have a preventive role in melanoma occurrence or potentiate the anticancer effects of NK-cell immune therapy. Heat shock proteins (HSPs) are evolutionarily conserved proteins induced by cell stress such as heat, oxidative stress, and hypoxia [21]. HSPs are molecular chaperones that are classified into families according to their molecular weight and function as chaperones [22]. HSPs have multiple functions in gene expression, DNA replication, signal transduction, and apoptosis [23]. Hsp60 is a mitochondrial protein known to assist protein folding in prokaryotes and eukaryotes [24]. Hsp60 is also found in cytoplasm, and both forms of Hsp60 can function in pro-survival or pro-apoptotic pathways, depending on the cell type [25]. It is reported that Hsp60 may trigger apoptosis through caspase cascade activation via an association between Hsp60/Hsp10 complex and pro-caspase-3 [26]. Although Hsp60 plays important roles in various biological events, the exact molecular roles of Hsp60 in melanoma are poorly understood, and the relationship between 1a,25(OH) 2 D 3 and Hsp60 has not been reported.In 2938that on cancer cells, Fas delivers an apoptotic signal after engagement of Fas ligand on NK cells [15]. Additionally, ULBP2 and MICA/B are known ligands for NK-activating receptor, NKG2D[30]. Among those molecules tested, the expression of Fas was increased by 1a,25(OH) 2 D 3 treatment in G-361 and SK-MEL-5 cells ( Fig. 2A). However, the expression of ULBP2 and MICA/B was not increased by 1a,25(OH) 2 D 3 (data not shown). The expression of Fas showed maximum level at 72 h incubation (M1 gated 5 51.370.9% compared to 37.571.7% in control) (Fig. 2B). mRNA expression of Fas also increased following treatment with 1a,25(OH) 2 D 3 (1.9-fold) (Fig. 2C). From these d...

Effects of Vitamin D3, Calcipotriol and FTY720 on the Expression of Surface Molecules and Cytolytic Activities of Human Natural Killer Cells and Dendritic Cells

“…Lee et al . showed that vitamin D 3 activates NK cells to kill melanoma cells, an activity related to FAS up-regulation and induction of apoptosis [36]. In another study it was shown that NK cells by releasing IL-8 recruit eosinophils in allergic rhinitis, an effect that is inhibited by vitamin D 3 , indicating that this vitamin may play an important role as an anti-inflammatory molecule [37].…”

D-livering the message: The importance of vitamin D status in chronic liver disease

“…Studies in VDR knockout mice have shown that expression of VDR is necessary for NK cell development and function [114]. 1a,25(OH) 2 D enhances NK cell cytotoxicity [115] and suppresses DC maturation, inducing a more tolerant DC phenotype which, at the interface of the innate and adaptive immune systems, promotes T regulatory (Treg, CD4+CD25+) cell activity [116].…”

Vitamin D and Cancer

“…Recent investigations show that 1,25(OH)2D3 reduces the number of CPDs in human keratinocytes after UV-B radiation (Lee and Youn, 1998; De Haes et al, 2004; Trémezaygues et al, 2006). Interestingly Lee et al (2011) demonstrated that calcitriol exert anticancer effects enhancing natural killer (NK) cells susceptibility of human melanoma cells lines: 1,25(OH)2D-resistant melanoma cells treated with 1,25(OH)2D showed higher susceptibility to NK cells via heat shock protein 60 (Hsp60)-mediated up-regulation of FAS expression. Melanoma cells, in addition to expressing the VDR, are able to synthesize 1,25(OH)2D from 25(OH)D and proliferate much more slowly in the presence of calcitriol.…”